A riser pipe is made up of an assembly of tubular elements assembled by connectors. The tubular elements generally consist of a main tube provided with a connector at each end thereof. The main tube is fitted with auxiliary lines commonly referred to as “kill line”, “choke line”, “booster line” and “hydraulic line”, which allow circulation of a technical fluid to the well and of a formation fluid to the surface. The tubular elements are assembled on the drilling site, from a floater. The riser pipe is lowered into the water depth as the tubular elements are assembled, until the wellhead located on the sea bottom is reached.
In the perspective of drilling at water depths that can reach 3500 m or more, the weight of the riser pipe becomes very penalizing. This phenomenon is increased by the fact that, for the same maximum working pressure, the length of the riser requires a larger inside diameter for the auxiliary lines considering the necessity to limit pressure drops.
Besides, the necessity to decrease the riser pipe assembly time is all the more critical since the water depth, and therefore the riser length, are great.
Documents FR-2,891,577 (U.S. Pat. No. 7,762,337), FR-2,891,578 and FR-2,891,579 (U.S. Pat. No. 8,037,939) describe various solutions notably aiming to involve the auxiliary lines, together with the main tube, in the taking up of the longitudinal stresses undergone by the riser pipe.
The present invention describes an alternative solution providing a compact connector design well suited for deep-sea risers, i.e. located at depths greater than 2000 meters.